In this opinion article, we discuss the application of critical realism as an alternative model to the biopsychosocial model in the understanding of psychiatric disorders. Critical realism presents a stratified view of reality and recognises mental disorders as emergent phenomena; that is, their full explanation cannot be reduced to explanations at any lower level of biological processes alone. It thus underscores the significance of the depth of ontology, the interaction between agency and structure, and the context dependency and complex nature of causality. Critical realism provides the conceptual and epistemological basis for a more subtle understanding of the aetiology of psychiatric conditions, which is polyfactorial and includes biological, psychological and social dimensions. Through the realisation of the conceptual and applicative shortcomings in the biopsychosocial model, critical realism promises to advance the understanding of mental disorders and enable a more holistic approach to the problem of people with mental disorders.